It is highly desirable to be able to operate engines on alternative fuels. Currently, federal regulations require that the electronic control systems on new vehicles remain intact. That is, they cannot be modified to accept an alternative fuel supply system. Accordingly, the practice has been to provide the factory installed fuel system or primary fuel system and to install a totally separate and free-standing alternative fuel system.
As a result of the above, it has been necessary to provide separate sensors for the various engine functions that are utilized in determining the amount of fuel to be supplied to the engine, a separate electronic control module that receives signals from such sensors and converts them into a usable fuel signal. The provision of such apparatus is expensive and unnecessary.
U.S. Pat. No. 4,641,625 issued Feb. 10, 1987 to Peter R. Smith illustrates a fuel control system wherein liquid fuel and gaseous fuel are both utilized in the engine. In this instance, totally separate flow control systems exist side by side in connection with the engine. The systems are interrelated to the extent that the proportions of a liquid fuel and gaseous fuel can be varied in the event that it is desirable to combine the two fuels.
U.S. Pat. Nos. 4,481,908 issued Nov. 13, 1984 to Katsuyoshi Iida and 4,706,630 issued Nov. 17, 1987 to Wineland, et al. are illustrative of the many patents issued related to mixtures of two fuels and the methods of controlling the proportions of the mixtures in engines.